Writable and Recyclable Cellulose-Stabilized Ga Ink for Deformable Negative Electrode of Flexible Aluminum Battery

Wearable and deformable electronics must be driven by safe and flexible batteries. Aluminum battery is an intrinsically safe energy storage device, but can not meet flexible requirements due to the rigid Al foil negative electrode. This work proposed a writable and recyclable cellulose nanofiber-stabilized liquid gallium (CNF-Ga) ink to prepare a deformable and self-healing negative electrode for the construction of a flexible and wearable aluminum battery. CNF-Ga ink was designed, and Ga nanoparticles (∼441 nm) were well dispersed. Flexible polyethylene terephthalate (PET) substrate was patterned by writing and rolling to obtain a CNF-Ga/PET electrode. Resistance changes of CNF-Ga/PET electrode under bending and twisting were negligible, and the electrode maintained structural integrity with nearly unchanged resistivity even after 1000 bending and twisting cycles. CNF-Ga/PET negative electrode exhibited excellent cycling stability for 1200 h. CNF-Ga‖carbon paper full aluminum battery possessed excellent charge/discharge properties and can be wrapped around the wrist. CNF-Ga can be recycled by NaOH to recover liquid Ga and regenerate CNF-Ga ink. This work provides a promising strategy to construct flexible aluminum batteries and wearable electronics.